And rightly so, it would seem, with echoes of the 2001 dot com bubble burst ringing in their ears.

After apparently being rebuffed by Snapchat with a $3bn offer, Facebook thought it appropriate to fork out over five times that on the privately owned Whatsapp, which has 450m users.

And to add more dot-bubble fuel to the fire, if it were necessary, Rakuten paid about $900m for a similar company to Whatsapp – Viber - just a few days ago.

In addition, analysis from Bloomberg shows us that the only other companies in the US that fetch such lofty valuations of about 19 times estimated sales are drugmakers that are developing treatments for cancer, Crohn’s disease and other serious ailments.

So what the hell is going on?

It would appear that Facebook, which is currently valued by the market at over $170bn, and its founder Mark Zuckerberg, sees Whatsapp as some kind of wonder drug.

But it is also a strategic move, and possibly a very good one.

Facebook was late to the messaging market itself and yesterday Zuckerberg said Whatsapp is “on a path to reach over 1 billion people worldwide in the next few years.”

According to the Whatsapp model, new subscribers use it for free for the first year and are charged 99 cents per year after that - if it can get to a billion users then the price paid may look a little less mad.

Still, it’s a massive bet.

There’s no doubt that the app was too far ahead to catch up and it is a way for Facebook, which many feel is losing its touch with the younger generation, to reach out to them again.

And potentially it gives Facebook a much wider spread into emerging markets like Asia, particularly China where Facebook’s site has been blocked since 2009 making it impossible for its to access a potential market of 600m.

There are caveats here too, of course.

Local service WeChat is widely available in China but many users are reluctant to use it because they fear their conversations are being monitored.

Having said that, if China doesn’t like something it has no qualms about killing the problem.

Investors in Facebook, no doubt, are hoping Zuckerberg’s big bet is right but it is no surprise that Facebook shares fell on the news.

Looking back, some of us are old enough to remember 2001 and the impact the dot com burst had on global markets.

Interestingly, the Whatsapp is the biggest technology acquisition since Time Warner’s $124bn merger with AOL in that year.

On a more positive, note, the Whatapp story is a classic rags to riches story.

The company’s founder Jan Koum moved to California from the Ukraine when he was sixteen and he signed the $19bn deal at a welfare centre where he used to collect handouts.

Everybody loves a success story, especially in the somewhat less cynical US.